Gas-solid interactions - Laboratory paradigms for reactions on interstellar grains
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Klein, R.↗
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Visual search in a forced-choice paradigm
The processing of visual information was investigated in the context of two visual search tasks. The first was a forced-choice task in which one of two alternative letters appeared in a visual display of from one to five letters. The second task included trials on which neither of the two alternatives was present in the display. Search rates were estimated from the slopes of best linear fits to response latencies plotted as a function of the number of items in the visual display. These rates were found to be much slower than those estimated in yes-no search tasks. This result was interpreted as indicating that the processes underlying visual search in yes-no and forced-choice tasks are not the same.
Holmgren, J. E.↗
Loudness enhancement and decrement in four paradigms
When one tone burst (the conditioner) preceeds another (the target) by 100 ms, target loudness is enhanced if the conditioner is more intense and decreased if it is less intense. We show here that similar loudness enhancements and decrements occur when the conditioner follows the target. In all instances, monaural loudness enhancements (in which the conditioner and target are delivered to the same ear) are greater than the dichotic enhancements (in which the conditioner is presented contralaterally), but the decrements, which are smaller than the enhancements, are similar in magnitude. Loudness enhancements and decrements are similar to sequential loudness effects and central tendency effects; the major difference is the relatively very large increases in loudness obtainable in loudness enhancement experiments. We outline a mechanism to account for these loudness phenomena and suggest that this mechanism is responsible for similar perceptual effects that occur in other stimulus dimensions and modalities.
Elmasian, R.↗
Social issues and implications of remote sensing applications: Paradigms of technology transfer
The transfer of technology from one federal agency to another was observed in the case of the move of LANDSAT to NOAA. An array of unanticipated consequences was found that have important impacts on both the process and outcome of the transfer. When the process was studied from viewpoint of the ultimate recipient, a set of expectations and perceptions were found that figure more in a final assessment than do the attributes of the technology being transfered. The question of how to link a technology with a community of potential users was studed in detail.
Hoos, I. R.↗
Data vs. information: A system paradigm
The data system designer requires data parameters, and is dependent on the user to convert information needs to these data parameters. This conversion will be done with more or less accuracy, beginning a chain of inaccuracies which propagate through the system, and which, in the end, may prevent the user from converting the data received into the information required. The concept to be pursued is that errors occur in various parts of the system, and, having occurred, propagate to the end. Modeling of the system may allow an estimation of the effects at any point and the final accumulated effect, and may prove a method of allocating an error budget among the system components. The selection of the various technical parameters which a data system must meet must be done in relation to the ability of the user to turn the cold, impersonal data into a live, personal decision or piece of information.
Billingsley, F. C.↗
Design and control strategies for CELSS - Integrating mechanistic paradigms and biological complexities
Systems analysis and control theory consideration are given to simulations of both individual components and total systems, in order to develop a reliable control strategy for a Controlled Ecological Life Support System (CELSS) which includes complex biological components. Because of the numerous nonlinearities and tight coupling within the biological component, classical control theory may be inadequate and the statistical analysis of factorial experiments more useful. The range in control characteristics of particular species may simplify the overall task by providing an appropriate balance of stability and controllability to match species function in the overall design. The ultimate goal of this research is the coordination of biological and mechanical subsystems in order to achieve a self-supporting environment.
Moore, B., III↗
Paradigm transition in cosmic plasma physics
New discoveries in cosmic plasma physics are described, and their applications to solar, interstellar, galactic, and cosmological problems are discussed. The new discoveries include the existence of double layers in magnetized plasmas and in the low magnetosphere, and energy transfer by electric current in the auroral circuit. It is argued that solar flares and the solar wind-magnetosphere interaction should not be interpreted in terms of magnetic merging theories, and that electric current needs to be explicitly taken account of in understanding these phenomena. The filamentary structure of cosmic plasmas may be caused by electric currents in space, and the pinch effect may have a central role to play in the evolutionary history of interstellar clouds, stars, and solar systems. Space may have a cellular structure, with the cell walls formed by thin electric current layers. Annihilation may be the source of energy for quasars and the Hubble expansion, and the big bang cosmology may well be wrong.
Alfven, H.↗
The earth as a planet - Paradigms and paradoxes
The independent growth of the various branches of the earth sciences in the past two decades has led to a divergence of geophysical, geochemical, geological, and planetological models for the composition and evolution of a terrestrial planet. Evidence for differentiation and volcanism on small planets and a magma ocean on the moon contrasts with hypotheses for a mostly primitive, still undifferentiated, and homogeneous terrestrial mantle. In comparison with the moon, the earth has an extraordinarily thin crust. The geoid, which should reflect convection in the mantle, is apparently unrelated to the current distribution of continents and oceanic ridges. If the earth is deformable, the whole mantle should wander relative to the axis of rotation, but the implications of this are seldom discussed. The proposal of a mantle rich in olivine violates expectations based on evidence from extraterrestrial sources. These and other paradoxes force a reexamination of some long-held assumptions.
Anderson, D. L.↗
The electromagnetic ram action of the plasma focus as a paradigm for the generation of cosmic rays and the gigantic jets in active galaxies
Recent measurements of the energy spectrum of the plasma-focus-generated deuteron beam yield as spectrum of the form N(E)=(approx.) E to the -2.7 for 1MeV E 13 MeV. Other measurements show that the beta 1 electron beam which is generated simultaneously with the deuteron beam is interrupted into segments of spacing 25ps and duration approximately 4ps. A stuttering-electro-magnetic-ram (ser) model of the plasma focus in proposed which is similar to Raudorf's electronic ram which produces a similar spectrum for an electron beam for 1Mev E 10MeV. It is proposed that the cosmic ray spectrum and the giganic galactic jets are both generated by ser action near the centers of active galaxies.
Bostick, W. H.↗
Magnetic flux ropes of Venus - A paradigm for helical magnetic structures in astrophysical systems
Theoretical model of the helical structures in the magnetic flux ropes of Venus are presented. The models are based on observations carried out by the Pioneer Venus Orbiter. The densities of the magnetic currents flowing parallel and perpendicular to the Venusian magnetic field are obtained and a 'helical kink' criterion is developed to evaluate the stability of the ropes with respect to pinch-related perturbations. The arbitrary transversal of a helical flux rope by a kink instability is shown in a drawing.
Elphic, R. C.↗
Evolution of the inner asteroid belt: Paradigms and paradoxes from spectral studies
Recent years have witnessed a significant increase in the sophistication of asteroidal surface material characterizations derived from spectral data. An extensive data base of moderate to high spectral resolution, visible and near-infrared asteroid spectra is now available. Interpretive methodologies and calibrations were developed to determine phase abundance and composition in olivine-pyroxene assemblages and to estimate NiFe metal abundance from such spectra. A modified version of the asteroid classifications system more closely parallels the mineralogic variations of the major inner belt asteroid types. These improvements permit several general conclusions to be drawn concerning the nature of inner belt objects; their history, and that of the inner solar system; and the relationship between the asteroids and meteorites. Essentially all large belt asteroids have or are fragments of parent bodies which have undergone strong post-accretionary heating, varying degrees of melting and magmatic differentiation, and subsequent collisional disruption. These asteroids show a systematic, but not yet well characterized, mineralogic variation with semi-major axis. This suggests that the S-type asteroid families represent relatively recent collisions onto the cores of previously disrupted parent bodies.
Gaffey, Michael J.↗
Paradigm For Statistical Analysis Of Threshold Detection
Relative values assigned to double mistakes and changed iteratively. Method for statistical analysis of threshold detection saves experimental time by enabling use of same set of measurements with respect to two thresholds. Accounts for double mistakes, unresolvable by threshold-detection technique.
Diner, Daniel B.↗
Cretaceous-Tertiary findings, paradigms and problems
The asteroid hypothesis has stimulated numerous studies of the paleontological record at Cretaceous/Tertiary time as well as of geological indicators of environmental crisis preserved in the rock record. Both extinctions and geological anomalies often occur at times that do not appear to be synchronous or instantaneous. The record includes paleontological indicators of dinosaurs, terrestrial flora, marine planktonic organisms, and shallow water marine macrofauna and geological phenomena include occurrences of iridium and other platinum metals, trace elements, clay mineralogy, shocked minerals, soot, microspherules, and isotopes of osmium, strontium and carbon. These findings are reviewed in the context of the alternate hypotheses of an exogenic cause, involving either a single asteroid impact or multiple commentary impacts, and an endogenic cause, involving intense global volcanism and major sea level regression.
Officer, C. B.↗
Object Oriented Programming Systems (OOPS) and frame representations: An investigation of programming paradigms
The project was initiated to research Object Oriented Programming Systems (OOPS) and frame representation systems, their significance and applicability, and their implementation in or relationship to Ada. Object orientated is currently a very popular conceptual adjective. Object oriented programming, in particular, is promoted as a particularly productive approach to programming; an approach which maximizes opportunities for code reuse and lends itself to the definition of convenient and well-developed units. Such units are thus expected to be usable in a variety of situations, beyond the typical highly specific unit development of other approaches. Frame represenation systems share a common heritage and similar conceptual foundations. Together they represent a quickly emerging alternative approach to programming. The approach is to first define the terms, starting with relevant concepts and using these to put bounds on what is meant by OOPS and Frames. From this the possibilities were pursued to merge OOPS with Ada which will further elucidate the significant characteristics which make up this programming approach. Finally, some of the merits and demerits of OOPS were briefly considered as a way of addressing the applicability of OOPS to various programming tasks.
Auty, David↗
Hollow conical jet models for SS 433 - A paradigm lost?
A precessing jet such as that in SS 433 may be approximated as an axisymmetric flow, if the precession time is short by comparison to the propagation time. A series of simulations has been conducted for precessing jets using an axisymmetric finite-difference hydrodynamics code. Examinations are made of hollow cylindrical jets, which lack the complication of a growing interior volume, and conical jets, which model the behavior of a precessing jet propagating on the surface of its precession cone.
Kochanek, Christopher S.↗
The supermodule - A design departure from the Shuttle payload paradigm
An effort has been made to formulate a novel approach to the construction of manned orbital facilities, in the context of a long-term launch strategy. The pressurized volume component of a manned platform is the point of departure, and an integrated vehicle designated the 'Supermodule' is defined which replaces analogous Space Station Freedom pressurized volume components. A launch sequence encompassing one Supermodule, one Shuttle Orbiter, and three Shuttle-Derived Vehicle cargo launchers, could reduce the number of launches needed to build a Space Station of the size of Freedom from 20 to merely five.
Murbach, Marcus S.↗
The effects of speech controls on performance in advanced helicopters in a double stimulation paradigm
The potential benefit of speech as a control modality has been investigated with mixed results. Earlier studies suggests that speech controls can reduce the potential of manual control overloads and improve time-sharing performance. However, these benefits were not without costs. Pilots reported higher workload levels associated with the use of speech controls. To further investigate these previous findings, an experiment was conducted in a simulation of an advanced single-pilot, scout/attack helicopter at NASA-Ames' ICAB (interchangeable cab) facility. Objective performance data suggested that speech control modality was effective in reducing interference of discrete, time-shared responses during continuous flight control activity. Subjective ratings, however, indicated that the speech control modality increased workload. Post-flight debriefing indicated that these results were mainly due to the increased effort to speak precisely to a less than perfect voice recognition system.
Bortolussi, Michael R.↗
Automated support for system's engineering and operations - The development of new paradigms
Technological developments in spacecraft ground operations are reviewed. The technological, operations-oriented, managerial, and economic factors driving the evolution of the Mission Operations Control Center (MOCC), and its predecessor the Operational Control Center are examined. The functional components of the various MOCC subsystems are outlined. A brief overview is given of the concepts behind the The Knowledge-Based Software Engineering Environment, the Generic Spacecraft Analysis Assistant, and the Knowledge From Pictures tool.
Truszkowski, Walt↗